Refractory metal tungsten&moly tungsten wire is a rare , high-temperature
hardness of the steel can be improved , the sixth period of
the periodic table are ( second long cycle) Ⅵ B family.
tungsten weights is a silvery-white metal that looks like steel.
Tungsten high melting point, low vapor pressure , evaporation
rate is also small . Tungsten is chemically stable at room
temperature when not react with air and water when not
heated, any concentration of hydrochloric acid, sulfuric
acid, nitric acid, hydrofluoric acid and aqua regia tungsten tube
are ineffective when the temperature was raised to 80 ° -100
when ° C, these various acids , except hydrofluoric acid ,
the other weak acid on the role of tungsten occur . At room
temperature , can be quickly dissolved in a mixture of
tungsten acid, hydrofluoric acid and concentrated nitric acid
, it does not work in an alkaline solution. The presence of
air under the conditions of the tungsten oxide can be melted
into the base tungstate , in the presence of an oxidant
(NaNO3, NaNO2, KClO3, PbO2) exists , the generation of a more
violent reaction tungstate . High temperature with chlorine,
bromine , iodine , carbon, nitrogen , sulfur and other
compounds , but not together with the hydrogenation .
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